Mimic Ion Channels

“By creating nanopores in the membrane, we can use the membrane to separate charged species or regulate the flow of charged molecules and ions, thereby mimicking the operation of biological ion channels,“ said lead researcher Jean-Pierre Leburton, the Stillman Professor of Electrical and Computer Engineering at Illinois.

Leburton simulated the operation of the semiconductor membrane at a number of electrostatic potentials. In the researchers’ model, the nanopore-membrane structure is made of two layers of silicon, each 12 nanometers thick, with opposite (n- and p-) doping. The electrostatic potential is positive on the n-side and negative on the p-side of the membrane.

The nanopore has an hourglass shape, with a neck 1 nanometer in diameter and openings on each side of the membrane 6 nanometers in diameter. The „size“ of the nanopore can be changed by changing the electrostatic potential around it. “By controlling the flow of ions, the artificial nanopore offers a degree of tunability not found in biological ion channels,” said Leburton.

In addition to serving as a substitute for biological ion channels, the solid-state nanopore and membrane could be used in other applications, including sequencing DNA.

“Using semiconductor technology to sequence the DNA molecule would save time and money,“ Leburton said. „By biasing the voltage across the membrane, we could pull DNA through the nanopore. Since each base pair carries a different electrical charge, we could use the membrane as a p-n junction to detect the changing electrical signal.“